Blast device for steel converter

ABSTRACT

Device for supplying blast gas to the blowing orifices of the bottom of a steelwork converter, which comprises a plurality of header-forming tubes disposed either as concentric tores or in any other suitable manner, each header being adapted to supply blast gas to a number of bottom orifices, for example a row thereof, with self-stopping means for easily putting each tuyere out of service in case of abnormally rapid wear thereof.

United States Patent [72] Inventors PierreL'eroy Appl. No. FiledPatented Priority 23, Rue de Tourville, St. Germain en Laye, 78;

Emile Sprunck, rue du Marechal Foch, Moyervre Grande, 57, both of,France 8,989

Feb. 5, 1970 Division of Ser. No. 739,553, June 24, 1968 Aug. 31, 1971July 5, 1967,,Iune 17, 1968 France 113,156 and 155,193

BLAST DEVICE FOR STEEL CONVERTER 10 Claims, 3 Drawing Figs.

u.s.c| 239/551,

239/558, 239/562, 239/559, 266/41 1nt.Cl B05b1/14 FieldofSearch 239/550,

[561' References Cited I UNITED STATES PATENTS 685.230 10/1901 Speirs239/2885 2,854,229 9/1958 Earle 266/41 2,977,108 3/1961 Cogelja et al.266/41 X 3,116,143 12/1963 Reichl 266/41 X 3,210,043 10/1965 Burzlaff251/320 Primary ExaminerMi Henson Wood, .Ir. Assistant Examiner-ThomasC. Culp, .lr. Attorney-Wenderoth, Lind & Ponack ABSTRACT: Device forsupplying blast gas to the blowing orifrees of the bottom of a steelworkconverter, which comprises a plurality of header-forming tubes disposedeither as concentric tores or in any other suitable manner, each headerbeing adapted to supply blast gas to a number of bottom orifices, forexample a row thereof, with self-stopping means for easily putting eachtuyere out of service in case of abnormally rapid wear thereof.

- Pmmmusal Ian snmmrg INVENTORS PIERRE LEROY ATTORNEYS PATENTEU M1831l97| SHEEI 2 m 2 %a v V as! INVENTORS RRE LEROY 47 LE SPRUNCK BLASTDEVICE FOR STEEL CONVERTER This application is a division of ourapplication Ser. No. 739,553 filed June 24, 1968, entitled Blast Devicefor Steel Converter."

This invention relates to a device for supplying air to be blown throughthe bottom of a steel converter, this device being particularlyadvantageous when the blast pressure exceeds 3 bars or 43 psi,

The conventional system for supplying air to the bottom of steelworkconverters comprises a so-called blowing box consisting of a simplecylindrical and relatively shallow chamber of a diameter slightlygreater than the diameter of the outermost circular row of tuyeres orblowing orifices. Its lateral wall comprises one or more large aperturesthrough which the air blast is directed. This blowing box is bounded atthe top by the baseplate supporting the converter bottom provided withblow holes, and at the bottom by a closing lid. By removing this lidaccess can be had to the blow holes in order to check their behavior inservice and, if necessary, either clear them or on the contrary blockthem up on purpose in case their wear were deemed abnormally rapid incomparison with that of adjacent holes. The removal of said lid is alsouseful for replacing a worn bottom with a new one at the end ofa run.

As a rule, this supply system is adequate for operating Bessemer orThomas process steel plants in which the blast pressure does not exceed3 bars (43.5 p.s.i.).

However, if more recent steelmaking processes are used, such as theblowing of pure oxygen or high-oxygen air through orifices of relativelysmall diameter, in which it may be desired to produce blasts underpressures considerably higher than those conventionally used in Bessemeror Thomas processes which, as already pointed out, do not exceed 3 bars(43.5 p.s.i.), the conventional blowing box cannot be used since itsoperation would be attended by the following inconveniences:

a. The blowing-box closing lid, of which the airtightness is alreadyinadequate under service pressures of the order of 1.5 to 3 bars (21 to43.5 p.s.i.), has a definitely poor airtightness when the pressureexceeds 3 bars (43.5 p.s.i.). As an alternative, the number oftightening devices for example of the stud and key type may beincreased, but in this case the opening and closing of this lid becomesa long and tedious operation. Moreover, the joint between the lid andthe box must be provided with a plastic gasket and it is clear thatalong such a great circumference the resulting fluidtightness cannot besatisfactory unless the box and lid are really distortion-free, acondition generally of short duration in the case of a new blowing box.

b. The use of blast pressures in excess of3 bars (43.5 p.s.i.) and evenin excess of 12 bars (174 p.s.i.) is attended by a considerablemultiplication of the risk of causing air leaks to take place betweenthe bottom plate and the base of the buyeres or blowing pipes, andtherefore of suddenly causing the complete refractory bottom to blow upunder the high air pressure.

c. If the blowing box diameter exceeds 2 meters-(6 feet 7 inch) theresultant of the pressure forces acting upon the bottom plate is veryimportant. Thus, under a l2-bar (174 psi.) pressure this resultant iswell above 375 tons. As a result, on the one hand a deformation of thebaseplate and the lid is observed during the pressure increment period,and on the other hand fatigue strain appears between the compression andexpansion phases.

It is the essential object of the present invention to provide a devicefor supplying an oxidizing blast to the blowing orifices or tuyeres atthe bottom of steelwork converter which is free of the drawbacks of aconventional blowing box and capable of operating satisfactorily underpressures in excess of 3 bars or 43.5 p.s.i.

To this end the present invention provides a device for supplying an airblast to the blowing orifices disposed through the bottom of steelworkconverters, said device consisting of a plurality of header tubes havingeither the shape of concentrically disposed tores, or any other suitableconfiguration, each header delivering air under pressure to a number ofbottom orifices, for example those of one row.

This invention may also have one or more of the following features takenseparately or in any combination:

a. The air blast header assembly is mechanically detachable as a unit;

b. The air blast header assembly is welded to the bottom plate;

c. The air blast header assembly itself is fed with blast air from asingle inlet, or from two or more inlets;

d. The supply of blast air to the headers is through or facilitated by,interconnecting ducts of which the number and contour are such that theyensure a uniform distribution of the air output to each blast tuyere ofthe set;

e. The supply headers and the interconnecting ducts are made ofsteel;

f. The supply headers and the interconnecting ducts are made of copper;

g. The set of supply headers is housed in a box, for example aconventional blast or blowing box, provided with a closing lid. Thefunction of this box is to protect the headers as a whole, and also themembers connecting these headers to the blowing orifices, against shocksor the projection of incandescent materials;

h. The supply headers are connected through flexible pipes to theblowing orifices fed therefrom,

i. The supply headers are connected to the blowing orifices throughpipes of relatively small diameter, such as copper pipes forming one ormore turns or coils, in order to impart a certain elasticity theretowhich may be useful during assembling and disassembling operations;

j. The flexible pipes as per (h) hereinabove or the small diameter pipesas per (i) are provided at least one of their ends, on the blowingorifice side, or at either ends, with selfstopping unions adapted toclose themselves automatically in a fluidtight manner when they aredisconnected;

k. The blowing orifices are provided with copper tubes of relativelysmall diameter and adapted to be connected or disconnected by simplyoperating the end union of the corresponding flexible pipe or smalldiameter pipe;

1. The assembly consisting of each union as per (j) hereinabove, of thelower end of the copper tube lining each blowing orifice and of thebottom baseplate, is so arranged that if an accidental blast leakagetook place as a consequence of the high pressure between the union andthe lower end of the copper tube, it would be vented to the freeatmosphere, so that it will not filtrate between the tube and the bottomplate;

m. If the supply headers are connected to the blowing orifices viaflexible piping as per (h) or small diameter pipes as per (i), theseheaders are each disposed between two adjacent rows of blowing orifices,in order to free the access to these orifices for inspection andmaintenance purposes in service, and also for disconnecting them in caseof abnormally fast wear thereof in comparison with that of adjacentorifices;

n. Each header welded to the baseplate engages directly a row of blowingorifices and receives therethrough, in front of each orifice, a movablenozzle provided with a valve member, the axis of said nozzle and theaxis of said valve being coincident with the axis of the correspondingblowing orifice;

o. In a device of the type set forth in paragraph (n) hereinabove, eachmetal tube, for example the copper pipe, constituting the blowingorifice of the converter bottom has a funnel-shaped lower end solderedor not to the plate supporting the bottom of the converter, and thenozzle has a semispherical upper end adapted to engage in a fluidtightmanner the inner wall of said funnel so as to press same against saidbottom plate; I

p. In a device of the type set forth in paragraphs (n) and (o) thehollow nozzle comprises coaxially to its upper end a cylindrical blowingorifice ending at the top with an outflared portion so that thesuccessive hammerings of the upper end of the nozzle will not alter thediameter of the cylindrical portion and therefore the gas outputcontrolled thereby;

q. In a device of the type set forth in paragraphs (n), (o), (p)hereinabove, the inner cavity of the nozzle which supplies air to thecylindrical orifice mentioned in paragraph (p), is adapted tocommunicate with the air under pressure contained in the header througha number of ducts of which the total cross-sectional passage area iscalculated with a view not to restrict the gas output;

r. In a device of the type set forth in paragraph (n), and (p)hereinabove, the valve member incorporated in the nozzle is a solidmember mounted in the nozzle and provided with a ball valve at its upperend, said ball valve being adapted to engage a seat consisting of theedge of the cylindrical orifice of the nozzle mentioned in paragraph (p)hereinabove, when it is desired to discontinue the operation of therelevant tuyere;

s. In a device according to (r) hereinabove the closing movement isobtained by screwing the valve member in the nozzle, or through anyother suitable means;

t. In a device of the type set forth above in paragraph (n), the base ofthe metal tube constituting each tuyere, which may be funnel-shaped asmentioned in paragraph (0), has formed in its outer face a communicationleading to a leakage duct formed in the bottom plate of the converter sothat in case of air leakage at the base of said funnel-shaped lower endthe air under pressure is directed to the outside, instead of betweenthe plate and the bottom, which would be particularly dangerous.

As will be readily understood, one of the essential advantagescharacterizing this invention is that the air blast under pressure iskept and led under pressure by using tubular supply headers, whethertoroidal or not, instead of causing this air to flow into a chamber ofrelatively great capacity, such as a conventional blowing box, thesubdivision of the blast into as many streams as there are blowingorifices taking place at the initial ends of the supply header tubes. Asa result, the air under pressure is constantly enclosed in tubes orpipes constituting the best possible type of container for keeping a gasunder pressure.

Another advantageous feature of this invention lies in the fact thateach blowing orifice can be connected and disconnected in an easy andquick way; in fact, the connection is obtained by using a special unionof known type that fits instantaneously to the base of the copper tubelining the interior of the blowing orifice; conversely, when the unionis disconnected from the tuyere tube the end of the flexible tube orpipe or of the small-diameter tube secured by its opposite end to thesupply ring is closed automatically. Alternately, the connection anddisconnection are responsive only to the simple actuation ofa valvemember in a nozzle.

It is a further advantage of this invention that if, as a consequence ofthe blast pressure, and air leakage takes place at the base of thecopper tube lining the relevant blowing orifice, any risk of causingthis air to leak between the tube and the bottom plate is definitelyprecluded, thus eliminating a serious risk, notably of raising theconverter bottom. In fact, the lower end of the copper tube is pressedwith force against a tapered surface of the baseplate, and the space inwhich the leakage is likely to take place constantly communicates withthe surrounding atmosphere.

Another advantageous feature characterizing this invention is that theaccess to the blowing orifices remains free, even without removing thesupply headers. A general advantage of this invention also lies in thefact that leakages of blast air under pressure are nearly nonexistantand that if they occurred accidentally at any point they can be stoppedimmediately.

With the above and other objects in view, a preferred embodiment of theinvention is shown in the drawings, in which:

FIG. 1 shows a general view of six headers supplying blast air and thecommunication ducts associated therein.

FIG. 2 is a vertical sectional view taken along Section Line 8-8 of FIG.1, and

FIG. 3 is a vertical sectional view taken along Section Line CC of FIG.1.

Pure oxygen, under a pressure of about 13 to 14 bars to 205 p.s.i.), issupplied to a converter capable of refining 20 tons of pig iron. To thisend, the bottom is provided with 162 blast holes lined internally withcopper piping having an inner diameter of 3.5 mm. (about 0.14 inches).

These 162 blast holes are distributed into six concentric circles orrows having the following diameters and number of orifices:

1st row: dia. dia. 400 mm. (15% inches) 12 holes 2nd row: dia. 625 mm.(24.6 inches) 18 holes 3rd row: dia. 850 mm. (33% inches) 24 holes 4thth row: dia. dia. 1,075 mm. (42%inches) 30 holes 5th row: dia. 1,300 mm.(51 inches) 36 holes 6th row: dia. 1,525 mm. (60 inches) 42 holes Theembodiment described herein with reference to the Figures of thedrawings comprises six headers disposed each beneath one of the six rowsof blast holes of the converter bottom.

The communication between the headers and the blast holes is obtained bymeans of one nozzle or injector per hole, each nozzle or injector beingprovided with a valve member.

FIG. 1 illustrates a general view of the six headers supplying the blastair, and the communication ducts associated therewith.

FIG. 2 is a vertical section showing the connection between the blastwind supply to the outermost header and one of the communication ducts,and

FIG. 3 is a vertical section showing a nozzle or injector with its valvemember registering both with one of the tuyeres.

FIG. 1 illustrates the six toroidal headers 21 to 26 corresponding tothe six rows of blast holes. The header 21 correspond to the peripheralrow.

These headers are interconnected by four communication ducts 27 to 30 ofwhich the cross-sectional passage area decreases towards, the center,according to a law ensuring a uniform distribution of the blast throughthe complete set of 162 blast holes.

The blast wind under pressure is supplied to the device through theinlet 31.

FIG. 2 is a section taken along the line 8-8 of FIG. 1 and shows adetail of the ingress of blast gas into the device.

The blast inlet duct 31 is welded both to plate 32 supporting theDolomite bottom of the converter (not shown) and to the peripheralconverter 31. The blast following the path shown by the arrow 33penetrates both into the peripheral header 21 and into the communicationduct 27. It penetrates through these two paths into the complete deviceconsisting of the six headers and the four communication ducts.

FIG. 3 is a section taken along the line CC of FIG. 1, Le. along theaxis of a blast tuyere, its nozzle or injector and its stop valve.

The bottom plate 32 supports the bottom 34 of the converter whichconsists of Dolomite and tar, or any other suitable refractory material.Orifices such as 35 are formed therethrough to permit the passage of thecopper pipes such as 36 constituting the metal portion of the tuyere.The base of the copper pipe is outflared and constitutes a kind offunnel37 soldered to the bottom plate 32. Moreover, the semispherical head 43of injector 42 is adapted to press the above-mentioned funnel-shaped end37 against the baseplate 32, whereby a theoretically completefluidtightness is obtained. Should one fraction of the blast underpressure seep accidentally to the outside of pipe 36, this gas would bedischarged via the leakage duct 38 and would thus be prevented fromattaining the underface of the Dolomites, by passing between the tube 36and plate 32.

The header 21 is welded at 39 to the baseplate 32.

At the location where the leakage duct 38 is machined the latter isclosed by adding some solder 40.

The chamber 41 of header 2] contains the blast gas, for example under apressure of 13 to 14 bars 190 to 205 p.s.i.).

The injector or nozzle 42 is a piece of revolution disposed coaxially tothe copper tube 36 extending through the wall of header 21 in aperfectly fluidtight manner. The semispherical head 43 of nozzle 42 isformed with an axial tappered bore 44 having substantially the shape ofan inverted frustum of a cone. At its lower end this bore 44 isconnected to a cylindrical bore 45 of a diameter at least equal to theinner diameter of tube 36. The nozzle 42 comprises a cylindrical innercavity 46 in which the valve member 47 and a ball valve 48 are adaptedto move axially. The blast position of valve member 47 is its lower mostposition. The chamber under pressure 46 of the header communicates withthe inner cavity 46 of the nozzle or injector through one or moreorifices such as 49 machined in the nozzle wall.

The bore 45 and tube 36 are thus supplied with blowing gas underpressure.

During the useful life of a converter bottom it may happen that theservice life of one or more tuyeres is considerably shorter than that ofthe other tuyeres, and that the worn tuyeres have to be put out ofservice. This is obtained by simply moving the valve member 47 upwardsuntil the ball valve 48 engages the bottom edge of bore 45, thus cuttingoff any communication between the cavity 46 of the nozzle and the coppertube 36. Under these conditions the tuyere 36 is put out of service andits wear and tear are discontinued immediately. The closing movement maybe obtained by screwing the valve member 47 in injector or nozzle 42, orthrough any other suitable means.

The fluidtightness between nozzle 42 and valve member 47 is obtained bydisposing two rubber or like packings 50 therebetween.

in principle, the injector or nozzle 42 is not moved during the entireservice life of the converter bottom. When this bottom is destroyed thenozzles or injectors are removed by maneuvering their heads 51.

Thus, the tuyere, its injector or nozzle and its valve member constitutean elongated unit of relatively small diameter and therefore of moderateoverall dimensions, which can be used even in systems comprising tuyeresdisposed at a relatively reduced spacing, as frequently observed inconverters.

Of course, it would not constitute a departure from the spirit and scopeof this invention to bring various modifications and variations in thepractical embodiment of the device constituting the subject-matterthereof, and even to contemplate the use of equivalent means.

We claim:

l. A device for supplying blast gas to the blowing orifices at thebottom of a steelwork converter having a base plate comprising aplurality of header tubes, each header tube having a plurality of bottomorifices, means supplying blast gas to a row of bottom orifices, each ofsaid header tubes welded to said baseplate engaging directly a row ofblowing orifices and receives therethrough, in alignment with eachorifice, a movable nozzle equipped with a valve member, the axes of saidnozzle and said valve member being aligned with the axis of the relevantblowing orifice.

2. A device as set forth in claim 1, wherein each blowing orifice formedthrough the converter bottom consists of a metal tube, for example acopper tube, each tube having a funnelshaped lower end adapted to besoldered to the plate supporting the converter bottom, and said nozzlehas a semispherical upper end adapted to engage in a fluidtight mannerthe inner wall of said funnel-shaped end by pressing same against saidbottom plate.

3. A device as set forth in claim 1 wherein each hollow nozzlecomprises, coaxially to its upper end, a cylindrical blowing orificeformed with an outflaring upper end to prevent the successive hammeringssupported by the upper end of the nozzle from damaging the diameter ofsaid cylindrical portion controlling the gas output.

4. A device as set forth in claim 2, wherein each hollow nozzlecomprises, coaxially to its upper end, a cylindrical blowing orificeformed with an outflaring upper end to prevent the successive hammeringssupported by the upper end of the nozzle from damaging the diameter ofsaid cylindrical portion controlling thegas output.

5. A device as set forth in claim 1 wherein the inner cavity of thenozzle which supplies blast gas to said cylindrical orifice is adaptedto communicate with the blast under pressure contained in the headerthrough a number of ducts of which the total cross-sectional passagearea is calculated with a view to avoid any limitation of the gasoutput.

6. A device as set forth in claim 2, wherein the inner cavity of thenozzle which supplies blast gas to said cylindrical orifices is adaptedto communicate with the blast under pressure contained in the headerthrough a number of ducts of which the total cross-sectional passagearea is calculated with a view to avoid any limitation of the gasoutput.

7 A device as set forth in claim 3, wherein the inner cavity of saidnozzle supplying said cylindrical orifice is adapted to communicate withthe blast under pressure contained in said header by means of a numberof ducts of which the total crosssectional passage area is calculatedwith a view to avoid any limitation of the gas output.

8. A device as set forth in claim 1, wherein the valve member of saidnozzle consists of a solid member disposed inside said nozzle andprovided with a ball valve at its top, said ball valve being adapted toengage the valve-sear forming lower edge of said cylindrical orifice ofsaid nozzle as a consequence of the movement of said valve member whenit is desired to put the corresponding tuyere out of service.

9. A device as set forth in claim 8, wherein said valve member movementis obtained by screwing same in said nozzle.

10. A device as set forth in claim 1, wherein the base of the metal tubeconstituting each tuyere, comprises on an outer face means permittingthe communication with a leakage duct formed in the bottom plate of theconverter whereby, in case of blast leakage at the base of saidfunnel-shaped base, the leakage under pressure is adapted to be ventedto the outside instead of against said plate and the bottom of theconverter.

1. A device for supplying blast gas to the blowing orifices at thebottom of a steelwork converter having a base plate comprising aplurality of header tubes, each header tube having a plurality of bottomorifices, means supplying blast gas to a row of bottom orifices, each ofsaid header tubes welded to said baseplate engaging directly a row ofblowing orifices and receives therethrough, in alignment with eachorifice, a movable nozzle equipped with a valve member, the axes of saidnozzle and said valve member being aligned with the axis of the relevantblowing orifice.
 2. A device as set forth in claim 1, wherein eachblowing orifice formed through the converter bottom consists of a metaltube, for example a copper tube, each tube having a funnel-shaped lowerend adapted to be soldered to the plate supporting the converter bottom,and said nozzle has a semispherical upper end adapted to engage in afluidtight manner the inner wall of said funnel-shaped end by pressingsame against said bottom plate.
 3. A device as set forth in claim 1wherein each hollow nozzle comprises, coaxially to its upper end, acylindrical blowing orifice formed with an outflaring upper end toprevent the successive hammerings supported by the upper end of thenozzle from damaging the diameter of said cylindrical portioncontrolling the gas output.
 4. A device as set forth in claim 2, whereineach hollow nozzle comprises, coaxially to its upper end, a cylindricalblowing orifice formed with an outflaring upper end to prevent thesuccessive hammerings supported by the upper end of the nozzle fromdamaging the diameter of said cylindrical portion controlling the gasoutput.
 5. A device as set forth in claim 1 wherein the inner cavity ofthe nozzle which supplies blast gas to said cylindrical orifice isadapted to communicate with the blast under pressure contained in theheader through a number of ducts of which the total cross-sectionalpassage area is calculated with a view to avoid any limitation of thegas output.
 6. A device as set forth in claim 2, wherein the innercavity of the nozzle which supplies blast gas to said cylindricalorifices is adapted to communicate with the blast under pressurecontained in the header through a number of ducts of which the totalcross-sectional passage area is calculated with a view to avoid anylimitation of the gas output. 7 A device as set forth in claim 3,wherein the inner cavity of said nozzle supplying said cylindricalorifice is adapted to communicate with the blast under pressurecontained in said header by means of a number of ducts of which thetotal cross-sectional passage area is calculated with a view to avoidany limitation of the gas output.
 8. A device as set forth in claim 1,wherein the valve member of said nozzle consists of a solid memberdisposed inside said nozzle and provided with a ball valve at its top,said ball valve being adapted to engage the valve-sear forming loweredge of said cylindrical orifice of said nozzle as a consequence of themovement of said valve member when it is desired to put thecorresponding tuyere out of service.
 9. A device as set forth in claim8, wherein said valve member movement is obtained by screwing same insaid nozzle.
 10. A device as set forth in claim 1, wherein the base ofthe metal tube constituting each tuyere, comprises on an outer facemeans permitting the communication with a leakage duct formed in thebottom plate of the converter whereby, in case of blast leakage at thebase of said funnel-shaped base, the leakage under pressure is adaptedto be vented to the outside instead of against said plate and the bottomof the converter.